I have a 1987 Formula 305 with edelbrock carb and headers. We just re did the intake manifold gasket and that fixed most of the idling problems. Still doing a bit of carb adjustment, but otherwise while accelerating it's not too bad. Slowing down, not so bad either. But when cruising at a set speed and rpm it'll make little lurch motions forward, every now and then accompanied by a rev increase. Anyone have any ideas? We think it might be I have no backpressure in the exhaust right now, but this seems too profound to do that.